In storage systems, in order to enhance availability, it is common to adopt a configuration where multiple storage media are installed in the system, and when write data received from a superior device such as a host computer is stored in the storage media, redundant data such as parity is computed based on the write data, and the write data and the parity are stored in different storage media. Normally, parity computation is executed by a controller (storage controller) in the storage system, but since the processing load of the storage controller is increased thereby, a technique can be adopted where a storage media is equipped with the function to calculate parity, so that the parity computation load is off-loaded from the storage controller to the storage media side.
For example, Patent Literature 1 discloses a storage system having multiple storage media and a storage controller for controlling the multiple storage media, wherein the storage media is equipped with a parity generating function. According to the storage system, when a write request of update data is received from the host computer, the storage controller transmits the update data to the storage media storing the data before update of the relevant update data. Next, the storage controller lets the storage media generate an intermediate parity from the update data and the data before update, and receives the intermediate parity generated by the storage media. Then, the received intermediate parity is transmitted to the storage media storing the parity corresponding to the update data. Finally, a data commitment command is transmitted to the respective storage media, by which the stored content of the storage media storing the data before update is committed to a state where the update data is stored therein, and in the storage media storing the parity, a parity after update is generated and stored based on the intermediate parity and the parity before update having been stored in the storage media.
Patent Literature 1 US Patent Application Publication No. 2013/0290773